An image reading apparatus in which when one or a plurality of original sheets are put on an original plate and are read, a desired image can be automatically cropped without previously setting a cropping method by a user is provided. A control method of such an image reading apparatus is also provided. The image on the original plate is read. The type of original sheet is discriminated on the basis of color characteristics information of the read image on the original plate. One of plural read image cropping methods is selected in accordance with the discriminated original sheet type. The read image on the original plate is cropped by the selected cropping method.